JERUSALEM – Syria, which lost its stranglehold on neighboring Lebanon after an emotional democratic uprising last year, is trying to force its way back into power through Hezbollah.

Hezbollah’s leader, Sheik Hassan Nasrallah, vowed this week to “put the masses in the streets and topple the Lebanese government” within 10 days if he isn’t given a larger role in the Beirut government.

That ultimatum set off a crisis that threatens the truce that ended last summer’s Israel-Hezbollah war.

Hezbollah is usually seen as the puppet movement of Iran. But the Shiite guerrillas also are armed and openly supported by Syria.

Syria controlled much of Lebanon for nearly 30 years, until being driven out by popular anger over the assassination of a former Lebanese prime minister, Rafik al-Hariri.

According to U.S. and Israeli officials, the current crisis is Syria’s way of destabilizing the fragile Lebanese democracy that pushed Syria out.

There are other motives involved.

The leader of Lebanon’s Druze community, Walid Jumbalat, said Hezbollah’s grab for political power was planned by Syrian President Hafez al-Assad as a way to stave off an international court investigation of Syrian involvement in Hariri’s car-bomb murder.

The Hezbollah-Syria-Iran axis is one of the topics now being discussed in Jerusalem by visiting U.S. intelligence chief John Negroponte and Israeli Prime Minister Ehud Olmert.

Olmert underlined the seriousness of the impending Lebanese crisis when he toured Israel’s northern border this week.